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1
Josephson, R. K. "Dissecting muscle power output." Journal of Experimental Biology 202, no. 23 (December 1, 1999): 3369–75. http://dx.doi.org/10.1242/jeb.202.23.3369.
Testo completoAbstract (sommario):
The primary determinants of muscle force throughout a shortening-lengthening cycle, and therefore of the net work done during the cycle, are (1) the shortening or lengthening velocity of the muscle and the force-velocity relationship for the muscle, (2) muscle length and the length-tension relationship for the muscle, and (3) the pattern of stimulation and the time course of muscle activation following stimulation. In addition to these primary factors, there are what are termed secondary determinants of force and work output, which arise from interactions between the primary determinants. The secondary determinants are length-dependent changes in the kinetics of muscle activation, and shortening deactivation, the extent of which depends on the work that has been done during the preceding shortening. The primary and secondary determinants of muscle force and work are illustrated with examples drawn from studies of crustacean muscles.
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Martin, James C. "Muscle Power." Exercise and Sport Sciences Reviews 35, no. 2 (April 2007): 74–81. http://dx.doi.org/10.1097/jes.0b013e31803eb0a0.
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Leonard, Patrick. "Muscle power." New Scientist 193, no. 2592 (February 2007): 23. http://dx.doi.org/10.1016/s0262-4079(07)60473-4.
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Carson, Louise. "Muscle power." Equine Health 2011, no. 2 (November 8, 2011): 16–18. http://dx.doi.org/10.12968/eqhe.2011.1.2.16.
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Blake, Ollie M., and James M. Wakeling. "Muscle coordination limits efficiency and power output of human limb movement under a wide range of mechanical demands." Journal of Neurophysiology 114, no. 6 (December 1, 2015): 3283–95. http://dx.doi.org/10.1152/jn.00765.2015.
Testo completoAbstract (sommario):
This study investigated the influence of cycle frequency and workload on muscle coordination and the ensuing relationship with mechanical efficiency and power output of human limb movement. Eleven trained cyclists completed an array of cycle frequency (cadence)-power output conditions while excitation from 10 leg muscles and power output were recorded. Mechanical efficiency was maximized at increasing cadences for increasing power outputs and corresponded to muscle coordination and muscle fiber type recruitment that minimized both the total muscle excitation across all muscles and the ineffective pedal forces. Also, maximum efficiency was characterized by muscle coordination at the top and bottom of the pedal cycle and progressive excitation through the uniarticulate knee, hip, and ankle muscles. Inefficiencies were characterized by excessive excitation of biarticulate muscles and larger duty cycles. Power output and efficiency were limited by the duration of muscle excitation beyond a critical cadence (120–140 rpm), with larger duty cycles and disproportionate increases in muscle excitation suggesting deteriorating muscle coordination and limitations of the activation-deactivation capabilities. Most muscles displayed systematic phase shifts of the muscle excitation relative to the pedal cycle that were dependent on cadence and, to a lesser extent, power output. Phase shifts were different for each muscle, thereby altering their mechanical contribution to the pedaling action. This study shows that muscle coordination is a key determinant of mechanical efficiency and power output of limb movement across a wide range of mechanical demands and that the excitation and coordination of the muscles is limited at very high cycle frequencies.
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Josephson, R. "Power output from a flight muscle of the bumblebee Bombus terrestris. II. Characterization of the parameters affecting power output." Journal of Experimental Biology 200, no. 8 (April 1, 1997): 1227–39. http://dx.doi.org/10.1242/jeb.200.8.1227.
Testo completoAbstract (sommario):
1. Length-tension relationships and work output were investigated in the intact, dorso-ventral flight muscle of the bumblebee Bombus terrestris. The muscle is an asynchronous muscle. Like other asynchronous flight muscles, it has high resting stiffness and produces relatively low active force in response to tetanic stimulation. 2. The muscle shows shortening deactivation and stretch activation, properties that result in delayed force changes in response to step changes in length, a phase lag between force and length during imposed sinusoidal strain and, under appropriate conditions, positive work output during oscillatory length change. 3. Work loops were used to quantify work output by the muscle during imposed sinusoidal oscillation. The curves relating net work per cycle with muscle length, oscillatory strain and oscillatory frequency were all roughly bell-shaped. The work-length curve was narrow. The optimum strain for net work per cycle was approximately 3 %, which is probably somewhat greater than the strain experienced by the muscle in an intact, flying bumblebee. The optimum frequency for net work output per cycle was 63 Hz (30 °C). The optimum frequency for power output was 73 Hz, which agrees well with the normal wing stroke frequency if allowance is made for the elevated temperature (approximately 40 °C) in the thorax of a flying bumblebee. The optimal strain for work output was not strongly dependent on oscillation frequency. 4. Resilience (that is the work output during shortening/work input during lengthening) for unstimulated muscle and dynamic stiffness (=stress/strain) for both stimulated and unstimulated muscles were determined using the strain (3 %) and oscillation frequency (64 Hz) which maximized work output in stimulated muscles. Unstimulated muscle is a good energy storage device. Its resilience increased with increasing muscle length (and increasing resting force) to reach values of over 90 %. The dynamic stiffness of both stimulated and unstimulated muscles increased with muscle length, but the increase was relatively greater in unstimulated muscle, and at long muscle lengths the stiffness of unstimulated muscle exceeded that of stimulated muscle. Effectively, dynamic stiffness is reduced by stimulation! This is taken as indicating that part of the stiffness in an unstimulated muscle reflects structures, possibly attached cross bridges, whose properties change upon stimulation.
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Fadhilah Ilmi, Dhiki, and Wahyuni. "Effects of Plyometric Zig-Zag Run and Single Leg Speed Hop Exercises on Agility and Leg Muscles Explosive Power in Football Players." Indonesian Journal of Medicine 9, no. 1 (January 10, 2024): 33–38. http://dx.doi.org/10.26911/theijmed.2024.09.01.05.
Testo completoAbstract (sommario):
Background: Futsal is a ball game played by each of 5 people. With the aim of putting the ball into the opponent's goal. Agility and explosive power are required, plyometrics are used to increase lower body muscle power and increase explosive power by training muscles to perform more movements in a shorter time. This study aimed to determine the effects of plyometric zig-zag run and single leg speed hop exercises on increasing agility and leg muscle explosive power in futsal players. Subject and Method: This was a quasi experiments with no control group. The study was carried out in Kendal, Central Java, from May to June 2023. Total sample of 21 futsal players was selected simple random sampling. The dependent variable was leg muscle agility and explosive power. The independent variables were plyometric zig-zag run and single leg speed hop exercises. Leg muscle agility was measured using the agility t-test. Leg musce explosive power was measured using standing broad jump test. The data were tested using paired t-test. Result: Mean score of leg muscle agility after plyometric zig-zag run was faster (Mean= 9.86 sec.; SD= 0.58) than before (Mean= 10.03 sec.; SD= 0.53), p<0.001. Mean score of leg muscle explosive power after single leg speed hop exercises was higher (Mean= 217.05 cm; SD= 12.46) than before (Mean= 200.67 cm; SD= 10.89), p<0.001.Conclusion: Plyometric zig-zag run improves leg muscle agilty. Single leg speed hop exercises improves leg muscle explosive power. Keyword: exercise, plyometric, zig-zag run, single leg speed hop, agility, muscle explosive power
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Fadhilah Ilmi, Dhiki, and Wahyuni. "Effects of Plyometric Zig-Zag Run and Single Leg Speed Hop Exercises on Agility and Leg Muscles Explosive Power in Football Players." Indonesian Journal of Medicine 9, no. 1 (January 10, 2024): 33–38. https://doi.org/10.26911/theijmed.2024.9.1.713.
Testo completoAbstract (sommario):
Background: Futsal is a ball game played by each of 5 people. With the aim of putting the ball into the opponent's goal. Agility and explosive power are required, plyometrics are used to increase lower body muscle power and increase explosive power by training muscles to perform more movements in a shorter time. This study aimed to determine the effects of plyometric zig-zag run and single leg speed hop exercises on increasing agility and leg muscle explosive power in futsal players. Subject and Method: This was a quasi experiments with no control group. The study was carried out in Kendal, Central Java, from May to June 2023. Total sample of 21 futsal players was selected simple random sampling. The dependent variable was leg muscle agility and explosive power. The independent variables were plyometric zig-zag run and single leg speed hop exercises. Leg muscle agility was measured using the agility t-test. Leg musce explosive power was measured using standing broad jump test. The data were tested using paired t-test. Result: Mean score of leg muscle agility after plyometric zig-zag run was faster (Mean= 9.86 sec.; SD= 0.58) than before (Mean= 10.03 sec.; SD= 0.53), p<0.001. Mean score of leg muscle explosive power after single leg speed hop exercises was higher (Mean= 217.05 cm; SD= 12.46) than before (Mean= 200.67 cm; SD= 10.89), p<0.001.Conclusion: Plyometric zig-zag run improves leg muscle agilty. Single leg speed hop exercises improves leg muscle explosive power. Keyword: exercise, plyometric, zig-zag run, single leg speed hop, agility, muscle explosive power
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Askew, Graham N., and Richard L. Marsh. "Muscle designed for maximum short-term power output: quail flight muscle." Journal of Experimental Biology 205, no. 15 (August 1, 2002): 2153–60. http://dx.doi.org/10.1242/jeb.205.15.2153.
Testo completoAbstract (sommario):
SUMMARYTake-off in birds at high speeds and steep angles of elevation requires a high burst power output. The mean power output of the pectoralis muscle of blue-breasted quail (Coturnix chinensis) during take-off is approximately 400 W kg-1 muscle, as determined using two independent methods. This burst power output is much higher than has been measured in any other cyclically contracting muscle. The power output of muscle is determined by the interactions between the physiological properties of the muscle, the stimulation regime imposed by the central nervous system and the details of the strain cycle, which are determined by the reciprocal interaction between the muscle properties and the environmental load. The physiological adaptations that enable a high power output to be achieved are those that allow the muscle to develop high stresses whilst shortening rapidly. These characteristics include a high myofibrillar density, rapid twitch contraction kinetics and a high maximum intrinsic velocity of shortening. In addition, several features of the strain cycle increase the power output of the quail pectoralis muscle. First, the muscle operates at a mean length shorter than the plateau of the length/force relationship. Second,the muscle length trajectory is asymmetrical, with 70 % of the cycle spent shortening. The asymmetrical cycle is expected to increase the power output substantially. Third, subtle deviations in the velocity profile improve power output compared with a simple asymmetrical cycle with constant lengthening and shortening rates. The high burst power outputs found in the flight muscles of quail and similar birds are limited to very brief efforts before fatigue occurs. This strong but short flight performance is well-suited to the rapid-response anti-predation strategy of these birds that involves a short flight coupled with a subsequent sustained escape by running. These considerations serve as a reminder that the maximum power-producing capacities of muscles need to be considered in the context of the in vivosituation within which the muscles operate.
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Peplowski, M. M., and R. L. Marsh. "Work and power output in the hindlimb muscles of Cuban tree frogs Osteopilus septentrionalis during jumping." Journal of Experimental Biology 200, no. 22 (November 1, 1997): 2861–70. http://dx.doi.org/10.1242/jeb.200.22.2861.
Testo completoAbstract (sommario):
It has been suggested that small frogs use a catapult mechanism to amplify muscle power production during the takeoff phase of jumping. This conclusion was based on an apparent discrepancy between the power available from the hindlimb muscles and that required during takeoff. The present study provides integrated data on muscle contractile properties, morphology and jumping performance that support this conclusion. We show here that the predicted power output during takeoff in Cuban tree frogs Osteopilus septentrionalis exceeds that available from the muscles by at least sevenfold. We consider the sartorius muscle as representative of the bulk of the hindlimb muscles of these animals, because this muscle has properties typical of other hindlimb muscles of small frogs. At 25 degrees C, this muscle has a maximum shortening velocity (Vmax) of 8.77 +/- 0.62 L0 s-1 (where L0 is the muscle length yielding maximum isometric force), a maximum isometric force (P0) of 24.1 +/- 2.3 N cm-2 and a maximum isotonic power output of 230 +/- 9.2 W kg-1 of muscle (mean +/- S.E.M.). In contrast, the power required to accelerate the animal in the longest jumps measured (approximately 1.4 m) is more than 800 W kg-1 of total hindlimb muscle. The peak instantaneous power is expected to be twice this value. These estimates are probably conservative because the muscles that probably power jumping make up only 85% of the total hindlimb muscle mass. The total mechanical work required of the muscles is high (up to 60 J kg-1), but is within the work capacities predicted for vertebrate skeletal muscle. Clearly, a substantial portion of this work must be performed and stored prior to takeoff to account for the high power output during jumping. Interestingly, muscle work output during jumping is temperature-dependent, with greater work being produced at higher temperatures. The thermal dependence of work does not follow from simple muscle properties and instead must reflect the interaction between these properties and the other components of the skeletomuscular system during the propulsive phase of the jump.
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Konow, Nicolai, Emanuel Azizi, and Thomas J. Roberts. "Muscle power attenuation by tendon during energy dissipation." Proceedings of the Royal Society B: Biological Sciences 279, no. 1731 (September 28, 2011): 1108–13. http://dx.doi.org/10.1098/rspb.2011.1435.
Testo completoAbstract (sommario):
An important function of skeletal muscle is deceleration via active muscle fascicle lengthening, which dissipates movement energy. The mechanical interplay between muscle contraction and tendon elasticity is critical when muscles produce energy. However, the role of tendon elasticity during muscular energy dissipation remains unknown. We tested the hypothesis that tendon elasticity functions as a mechanical buffer, preventing high (and probably damaging) velocities and powers during active muscle fascicle lengthening. We directly measured lateral gastrocnemius muscle force and length in wild turkeys during controlled landings requiring rapid energy dissipation. Muscle-tendon unit (MTU) strain was measured via video kinematics, independent of muscle fascicle strain (measured via sonomicrometry). We found that rapid MTU lengthening immediately following impact involved little or no muscle fascicle lengthening. Therefore, joint flexion had to be accommodated by tendon stretch. After the early contact period, muscle fascicles lengthened and absorbed energy. This late lengthening occurred after most of the joint flexion, and was thus mainly driven by tendon recoil. Temporary tendon energy storage led to a significant reduction in muscle fascicle lengthening velocity and the rate of energy absorption. We conclude that tendons function as power attenuators that probably protect muscles against damage from rapid and forceful lengthening during energy dissipation.
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Faulkner, J. A., E. Zerba, and S. V. Brooks. "Muscle temperature of mammals: cooling impairs most functional properties." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 259, no. 2 (August 1, 1990): R259—R265. http://dx.doi.org/10.1152/ajpregu.1990.259.2.r259.
Testo completoAbstract (sommario):
Our purpose was to study the effect of a decrease in skeletal muscle temperature on single and repeated shortening, isometric, and lengthening contractions of mammalian skeletal muscles. Fast extensor digitorum longus muscles of mice were studied in situ and in vitro at 25 and 35 degrees C. No difference in isometric force was observed, but maximum and sustained powers were reduced by 40 and 62%, respectively. With cooling, maximum power absorption, which is proportional to the external work required to lengthen the muscle, increased significantly at each velocity of lengthening from 0.5 to 4.0 optimum fiber length/s. The 10 degrees C decrease in muscle temperature produced a decrease in power that was primarily a result of the decrease in the velocity of shortening, whereas the increase in power absorption was likely due to an increase in the number of strongly bound cross bridges resulting from a decreased rate of detachment. During voluntary exercise at decreased muscle temperatures, maximum and endurance performances are inevitably impaired by the decreases in maximum and sustained power of individual motor units.
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Sponberg, S., and T. L. Daniel. "Abdicating power for control: a precision timing strategy to modulate function of flight power muscles." Proceedings of the Royal Society B: Biological Sciences 279, no. 1744 (July 25, 2012): 3958–66. http://dx.doi.org/10.1098/rspb.2012.1085.
Testo completoAbstract (sommario):
Muscles driving rhythmic locomotion typically show strong dependence of power on the timing or phase of activation. This is particularly true in insects' main flight muscles, canonical examples of muscles thought to have a dedicated power function. However, in the moth ( Manduca sexta ), these muscles normally activate at a phase where the instantaneous slope of the power–phase curve is steep and well below maximum power. We provide four lines of evidence demonstrating that, contrary to the current paradigm, the moth's nervous system establishes significant control authority in these muscles through precise timing modulation: (i) left–right pairs of flight muscles normally fire precisely, within 0.5–0.6 ms of each other; (ii) during a yawing optomotor response, left—right muscle timing differences shift throughout a wider 8 ms timing window, enabling at least a 50 per cent left–right power differential; (iii) timing differences correlate with turning torque; and (iv) the downstroke power muscles alone causally account for 47 per cent of turning torque. To establish (iv), we altered muscle activation during intact behaviour by stimulating individual muscle potentials to impose left—right timing differences. Because many organisms also have muscles operating with high power–phase gains ( Δ power / Δ phase ), this motor control strategy may be ubiquitous in locomotor systems.
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Hilton, Tiffany N., Lori J. Tuttle, Kathryn L. Bohnert, Michael J. Mueller, and David R. Sinacore. "Excessive Adipose Tissue Infiltration in Skeletal Muscle in Individuals With Obesity, Diabetes Mellitus, and Peripheral Neuropathy: Association With Performance and Function." Physical Therapy 88, no. 11 (November 1, 2008): 1336–44. http://dx.doi.org/10.2522/ptj.20080079.
Testo completoAbstract (sommario):
Background and Purpose The primary purpose of this study was to report differences in calf intermuscular adipose tissue (IMAT), muscle strength (peak torque), power, and physical function in individuals with obesity, diabetes mellitus (DM), and peripheral neuropathy (PN) compared with those without these impairments. A secondary purpose was to assess the relationship between IMAT and muscle strength, power, and physical function. Subjects and Methods Six participants with obesity, DM, and PN (2 women, 4 men; mean age=58 years, SD=10; mean body mass index=36.3, SD=5; mean modified Physical Performance Test [PPT] score=22, SD=3) and 6 age- and sex-matched control subjects without these impairments were assessed and compared in muscle strength, muscle power, physical functioning, and muscle and fat volume, including IMAT in the calf muscles. Muscle, adipose tissue, and IMAT volumes of each calf were quantified by noninvasive magnetic resonance imaging. Muscle strength and power of the plantar-flexor and dorsiflexor muscles were quantified using isokinetic dynamometry. The modified PPT was used to assess physical function. Results Leg muscle and fat volumes were similar between groups, although IMAT volumes were 2.2-fold higher in the subjects with obesity, DM, and PN (X̅=120 cm3, SD=47) than in the control subjects (X̅=54 cm3, SD=41). Muscle strength, muscle power, ratio of leg muscle power to leg muscle volume, and modified PPT scores were lower in subjects with obesity, DM, and PN compared with the control subjects. Discussion and Conclusion The data indicate that excess fat infiltration in leg skeletal muscles is associated with low calf muscle strength, low calf muscle power, and impaired physical function in individuals who are obese with DM and PN.
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Roberts, Thomas J., Emily M. Abbott, and Emanuel Azizi. "The weak link: do muscle properties determine locomotor performance in frogs?" Philosophical Transactions of the Royal Society B: Biological Sciences 366, no. 1570 (May 27, 2011): 1488–95. http://dx.doi.org/10.1098/rstb.2010.0326.
Testo completoAbstract (sommario):
Muscles power movement, yet the conceptual link between muscle performance and locomotor performance is poorly developed. Frog jumping provides an ideal system to probe the relationship between muscle capacity and locomotor performance, because a jump is a single discrete event and mechanical power output is a critical determinant of jump distance. We tested the hypothesis that interspecific variation in jump performance could be explained by variability in available muscle power. We used force plate ergometry to measure power produced during jumping in Cuban tree frogs ( Osteopilus septentrionalis ), leopard frogs ( Rana pipiens ) and cane toads ( Bufo marinus ). We also measured peak isotonic power output in isolated plantaris muscles for each species. As expected, jump performance varied widely. Osteopilus septentrionalis developed peak power outputs of 1047.0 ± 119.7 W kg −1 hindlimb muscle mass, about five times that of B. marinus (198.5 ± 54.5 W kg −1 ). Values for R. pipiens were intermediate (543.9 ± 96.2 W kg −1 ). These differences in jump power were not matched by differences in available muscle power, which were 312.7 ± 28.9, 321.8 ± 48.5 and 262.8 ± 23.2 W kg −1 muscle mass for O. septentrionalis , R. pipiens and B. marinus , respectively. The lack of correlation between available muscle power and jump power suggests that non-muscular mechanisms (e.g. elastic energy storage) can obscure the link between muscle mechanical performance and locomotor performance.
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Josephson, R. "Power output from a flight muscle of the bumblebee Bombus terrestris. III. Power during simulated flight." Journal of Experimental Biology 200, no. 8 (April 1, 1997): 1241–46. http://dx.doi.org/10.1242/jeb.200.8.1241.
Testo completoAbstract (sommario):
1. The work loop approach was used to measure mechanical power output from an asynchronous flight muscle, the dorso-ventral muscle of the bumblebee Bombus terrestris. Measurements were made at the optimum muscle length for work output at 30 &deg;C and at a muscle temperature (40 &deg;C) and oscillatory frequency (141&shy;173 Hz, depending on the size of the animal) characteristic of free flight. Oscillatory strain amplitude was adjusted to maximize power output. 2. There was much preparation-to-preparation variability in power output. Power output in the muscles with the highest values was slightly greater than 100 W kg-1. It is argued that there are many experimental factors which might reduce measured power output below that in the living bumblebee, and no obvious factors which might lead to overestimates of muscle power. The conclusion is that flight muscle in the intact bumblebee can produce at least 100 W kg-1.
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McNitt-Gray, Jill L. "Human Muscle Power." International Journal of Sport Biomechanics 4, no. 2 (May 1988): 178–79. http://dx.doi.org/10.1123/ijsb.4.2.178.
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Reid, Kieran F., and Roger A. Fielding. "Skeletal Muscle Power." Exercise and Sport Sciences Reviews 40, no. 1 (January 2012): 4–12. http://dx.doi.org/10.1097/jes.0b013e31823b5f13.
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Wen, Fangfang, and Shujun Yang. "Equipment-assisted training to improve the explosiveness and agility of football players." Molecular & Cellular Biomechanics 22, no. 3 (February 17, 2025): 1399. https://doi.org/10.62617/mcb1399.
Testo completoAbstract (sommario):
Main: Football players need to release power in a short time when they dribble or shoot quickly, so they need explosive power. Explosive power comes from muscle strength, and muscle strength comes from muscle mass. Result: Football players can increase leg muscle mass to increase the upper limit of muscle strength, the upper limit of explosive power, and the upper limit of jumping ability. Discussion: Agility ladder training (rope ladder) is mainly used to practice coordination, balance and agility. It can enhance the speed of lateral displacement, and also enable the feet to move faster and increase the frequency of steps. Football players need to do this training. During training, the toes should be stepped on the right rhythm, and the hips can be swung while stepping, allowing the body to twist to any angle. Combined with cross steps and single-foot in and out, it can greatly increase the flexibility of both offense and defense. Rope ladder training. It provides a great multi-plane dynamic warm-up, which can develop the connection between the brain and muscles, and is also good for eccentric contraction and stability. In addition, it can also enhance the reaction time to the ball and exercise the muscles of the feet. Methods: Short-distance sprinting can increase the activity of fast-twitch muscle fibers, which contribute most to explosive power. At the same time, dynamic weight training such as squats and box jumps can significantly increase the strength of lower limb muscles for football players. The increase in weight and number of repetitions in strength training should be gradual according to individual ability to avoid muscle damage. Focusing on strengthening the stability of the core muscles can effectively support the development of explosive power in the leg muscles. Conclusion: Football explosive power training can train the ability of muscle cycle lengthening and shortening, effectively utilize the elastic potential energy stored in the soft tissue during the lengthening process, reduce the energy consumption of direct muscle contraction, and improve explosive power energy.
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Wakeling, J. M., K. M. Kemp, and I. A. Johnston. "The biomechanics of fast-starts during ontogeny in the common carp cyprinus carpio." Journal of Experimental Biology 202, no. 22 (November 15, 1999): 3057–67. http://dx.doi.org/10.1242/jeb.202.22.3057.
Testo completoAbstract (sommario):
Common carp Cyprinus carpio L. were reared a constant temperature of 20 degrees C from the larval (7 mm total length) to the juvenile (80 mm) stage. Body morphology and white muscle mass distribution were measured. Fast-start escape responses were recorded using high-speed cinematography from which the velocities, accelerations and hydrodynamic power requirements were estimated. All three measures of fast-start performance increased during development. White muscle contraction regimes were calculated from changes in body shape during the fast-starts and used to predict the muscle force and power production for all longitudinal positions along the body. Scaling arguments predicted that increases in body length would constrain the fish to bend less rapidly because the cross-sectional muscle area, and hence force production, does not increase at the same rate as the inertial mass that resists bending. As predicted, the increases in body length resulted in decreases in muscle shortening velocity, and this coincided with increases in both the force and power produced by the muscles. The hydrodynamic efficiency, which relates the mechanical power produced by the muscles to the inertial power requirements in the direction of travel, showed no significant change during ontogeny. The increasing hydrodynamic power requirements were thus met by increases in the power available from the muscles. The majority of the increases in fast-start swimming performance during ontogeny can be explained by size-dependent increases in muscle power output. For all sizes, there was a decrease in muscle-mass-specific power output and an increase in muscle stress in a posterior direction along the body due to systematic variations in fibre strain. These changing strain regimes result in the central muscle bulk producing the majority of the power requirements during the fast-start, and this power is transmitted to the tail region of the fish and ultimately to the water via muscle in the caudal myotomes.
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Umam, Choirul, Oce Wiriawan, and Edy Mintarto. "EFFECT OF EXERCISE BENCH PRESS AND SITTING CALF WITH CHEST PRESS AND LEG PRESS TO POWERARM MUSCLE AND POWER LIMB MUSCLES." JIPES - JOURNAL OF INDONESIAN PHYSICAL EDUCATION AND SPORT 3, no. 2 (December 28, 2017): 57–69. http://dx.doi.org/10.21009/jipes.032.05.
Testo completoAbstract (sommario):
This research aims to examine:1) How big the effectofbench press and sitting calf exercises to arm muscle power and leg muscle power; 2) How big the effect of chest press and leg press exercises to arm muscle power and leg muscle power; 3)How big the effect difference between bench press and sitting calf exercises and chest press and leg press exercises to to arm muscle power and leg muscle power. Research subject was boy student of SMA Negeri 1 Manyar as many 36 students, with age span 15-17 years which divided to three groups. Experiment group I received bench press and sitting calf while the second ones received chest press and leg press and the third experiment group performed activities according to daily routines. This type of research was applied quantitative research with quasi experimental research methods. The research design applied non-randomized control group pretest-postest design. And data analysis used were t-test and MANOVA. The data collecting process was using a medicine ball to obtain arm muscle power data and jump DF for leg muscle power during pretest and posttest. The results showed the difference between the pretest and posttest means of each group, namely: experimental group I for arm muscle power = 28.3 leg muscle power = 51.1. The second experiment group for arm muscle power = 45.9, leg muscle power = 78.2. Experiment Group III for arm muscle power = 13.3, leg muscle power = 27.1. Based on the above analysis, it can be concluded that there was an increase in all dependent variables for each experimental group after received bench press and sitting calf, chest press and leg press exercises, whereas chest press and leg press exercises were more effective at increasing arm muscle power and leg muscle strength
 Keywords: Weight training, Bench Press, Calf Sitting, Chest Pres, Leg Press, Arm Muscles Power, Leg Muscle Power.
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Tan, Ming A., Franz K. Fuss, and Dhanjoo Ghista. "Muscle Power Indexing for Sports Applications(Sports Biomechanics)." Proceedings of the Asian Pacific Conference on Biomechanics : emerging science and technology in biomechanics 2004.1 (2004): 205–6. http://dx.doi.org/10.1299/jsmeapbio.2004.1.205.
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Roberts, Thomas J., and Emanuel Azizi. "The series-elastic shock absorber: tendons attenuate muscle power during eccentric actions." Journal of Applied Physiology 109, no. 2 (August 2010): 396–404. http://dx.doi.org/10.1152/japplphysiol.01272.2009.
Testo completoAbstract (sommario):
Elastic tendons can act as muscle power amplifiers or energy-conserving springs during locomotion. We used an in situ muscle-tendon preparation to examine the mechanical function of tendons during lengthening contractions, when muscles absorb energy. Force, length, and power were measured in the lateral gastrocnemius muscle of wild turkeys. Sonomicrometry was used to measure muscle fascicle length independently from muscle-tendon unit (MTU) length, as measured by a muscle lever system (servomotor). A series of ramp stretches of varying velocities was applied to the MTU in fully activated muscles. Fascicle length changes were decoupled from length changes imposed on the MTU by the servomotor. Under most conditions, muscle fascicles shortened on average, while the MTU lengthened. Energy input to the MTU during the fastest lengthenings was −54.4 J/kg, while estimated work input to the muscle fascicles during this period was only −11.24 J/kg. This discrepancy indicates that energy was first absorbed by elastic elements, then released to do work on muscle fascicles after the lengthening phase of the contraction. The temporary storage of energy by elastic elements also resulted in a significant attenuation of power input to the muscle fascicles. At the fastest lengthening rates, peak instantaneous power input to the MTU reached −2,143.9 W/kg, while peak power input to the fascicles was only −557.6 W/kg. These results demonstrate that tendons may act as mechanical buffers by limiting peak muscle forces, lengthening rates, and power inputs during energy-absorbing contractions.
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Ellington, C. P. "Power and efficiency of insect flight muscle." Journal of Experimental Biology 115, no. 1 (March 1, 1985): 293–304. http://dx.doi.org/10.1242/jeb.115.1.293.
Testo completoAbstract (sommario):
The efficiency and mechanical power output of insect flight muscle have been estimated from a study of hovering flight. The maximum power output, calculated from the muscle properties, is adequate for the aerodynamic power requirements. However, the power output is insufficient to oscillate the wing mass as well unless there is good elastic storage of the inertial energy, and this is consistent with reports of elastic components in the flight system. A comparison of the mechanical power output with the metabolic power input to the flight muscles suggests that the muscle efficiency is quite low: less than 10%.
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Suharjana, Suharjana, Eko Priyanto, and Japhet Ndayisenga. "Contribution of Leg Power, Arm Power, Stomach Muscle Power, and Back Muscle Power on Jumping Services." International Journal of Human Movement and Sports Sciences 8, no. 5 (October 2020): 240–48. http://dx.doi.org/10.13189/saj.2020.080512.
Testo completo
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James, Rob S., Robbie S. Wilson, and Graham N. Askew. "Effects of caffeine on mouse skeletal muscle power output during recovery from fatigue." Journal of Applied Physiology 96, no. 2 (February 2004): 545–52. http://dx.doi.org/10.1152/japplphysiol.00696.2003.
Testo completoAbstract (sommario):
The effects of 10 mM (high) and 70 μM (physiologically relevant) caffeine on force, work output, and power output of isolated mouse extensor digitorum longus (EDL) and soleus muscles were investigated in vitro during recovery from fatigue at 35°C. To monitor muscle performance during recovery from fatigue, we regularly subjected the muscle to a series of cyclical work loops. Force, work, and power output during shortening were significantly higher after treatment with 10 mM caffeine, probably as a result of increased Ca2+ release from the sarcoplasmic reticulum. However, the work required to relengthen the muscle also increased in the presence of 10 mM caffeine. This was due to a slowing of relaxation and an increase in muscle stiffness. The combination of increased work output during shortening and increased work input during lengthening had different effects on the two muscles. Net power output of mouse soleus muscle decreased as a result of 10 mM caffeine exposure, whereas net power output of the EDL muscle showed a transient, significant increase. Treatment with 70 μM caffeine had no significant effect on force, work, or power output of EDL or soleus muscles, suggesting that the plasma concentrations found when caffeine is used to enhance performance in human athletes might not directly affect the contractile performance of fatigued skeletal muscle.
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Hikmad Hakim, Anto Sukamto, Rahma Dewi, and Nurkadri. "Relationship of Power, Waist Muscle Flexibility, and Power Muscle Legs Against Smash Volleyball For FIK UNM Makassar Students." Kinestetik : Jurnal Ilmiah Pendidikan Jasmani 6, no. 3 (September 30, 2022): 560–67. http://dx.doi.org/10.33369/jk.v6i3.23732.
Testo completoAbstract (sommario):
Power Leg Muscle Power volleyball for FIK UNM Makassar students. The sample used in this study were FIK UNM Makassar students who took volleyball courses. Data analysis techniques used to test the hypothesis are normality test, linearity test, and correlation test. From the results of the first hypothesis correlation test, a significance value of 0.046 < 0.05 was obtained, so there was a significant relationship between power arm muscle smash. The results of the second hypothesis test have a significance value of 0.037 < 0.05, so there is a significant relationship between Waist Muscle Flexibility and Smash. The results of the third hypothesis test have a significance value of 0.032 < 0.05, so there is a significant relationship between Waist Muscle Flexibility and Smash. Based on the multiple correlation test in the summary model table, it is known that the magnitude of the relationship between arm muscle power, waist muscle flexibility and leg muscle power (simultaneously) on the smash results calculated by the correlation coefficient is 0.452, this indicates a moderate effect. Meanwhile, the simultaneous contribution or contribution of the arm muscle power variable with the flexibility of the waist muscles is 20.4% while 79.1% is determined by other variables.
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Rome, L. C., D. M. Swank, and D. J. Coughlin. "The influence of temperature on power production during swimming. II. Mechanics of red muscle fibres in vivo." Journal of Experimental Biology 203, no. 2 (January 15, 2000): 333–45. http://dx.doi.org/10.1242/jeb.203.2.333.
Testo completoAbstract (sommario):
We found previously that scup (Stenotomus chrysops) reduce neither their stimulation duration nor their tail-beat frequency to compensate for the slow relaxation rates of their muscles at low swimming temperatures. To assess the impact of this ‘lack of compensation’ on power generation during swimming, we drove red muscle bundles under their in vivo conditions and measured the resulting power output. Although these in vivo conditions were near the optimal conditions for much of the muscle at 20 degrees C, they were far from optimal at 10 degrees C. Accordingly, in vivo power output was extremely low at 10 degrees C. Although at 30 cm s(−)(1), muscles from all regions of the fish generated positive work, at 40 and 50 cm s(−)(1), only the POST region (70 % total length) generated positive work, and that level was low. This led to a Q(10) of 4–14 in the POST region (depending on swimming speed), and extremely high or indeterminate Q(10) values (if power at 10 degrees C is zero or negative, Q(10) is indeterminate) for the other regions while swimming at 40 or 50 cm s(−)(1). To assess whether errors in measurement of the in vivo conditions could cause artificially reduced power measurements at 10 degrees C, we drove muscle bundles through a series of conditions in which the stimulation duration was shortened and other parameters were made closer to optimal. This sensitivity analysis revealed that the low power output could not be explained by realistic levels of systematic or random error. By integrating the muscle power output over the fish's mass and comparing it with power requirements for swimming, we conclude that, although the fish could swim at 30 cm s(−)(1) with the red muscle alone, it is very unlikely that it could do so at 40 and 50 cm s(−)(1), thus raising the question of how the fish powers swimming at these speeds. By integrating in vivo pink muscle power output along the length of the fish, we obtained the surprising finding that, at 50 cm s(−)(1), the pink muscle (despite having one-third the mass) contributes six times more power to swimming than does the red muscle. Thus, in scup, pink muscle is crucial for powering swimming at low temperatures. This overall analysis shows that Q(10) values determined in experiments on isolated tissue under arbitrarily selected conditions can be very different from Q(10) values in vivo, and therefore that predicting whole-animal performance from these isolated tissue experiments may lead to qualitatively incorrect conclusions. To make a meaningful assessment of the effects of temperature on muscle and locomotory performance, muscle performance must be studied under the conditions at which the muscle operates in vivo.
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Santos, Paulo D. G., João R. Vaz, Paulo F. Correia, Maria J. Valamatos, António P. Veloso, and Pedro Pezarat-Correia. "Muscle Synergies Reliability in the Power Clean Exercise." Journal of Functional Morphology and Kinesiology 5, no. 4 (October 22, 2020): 75. http://dx.doi.org/10.3390/jfmk5040075.
Testo completoAbstract (sommario):
Muscle synergy extraction has been utilized to investigate muscle coordination in human movement, namely in sports. The reliability of the method has been proposed, although it has not been assessed previously during a complex sportive task. Therefore, the aim of the study was to evaluate intra- and inter-day reliability of a strength training complex task, the power clean, assessing participants’ variability in the task across sets and days. Twelve unexperienced participants performed four sets of power cleans in two test days after strength tests, and muscle synergies were extracted from electromyography (EMG) data of 16 muscles. Three muscle synergies accounted for almost 90% of variance accounted for (VAF) across sets and days. Intra-day VAF, muscle synergy vectors, synergy activation coefficients and individual EMG profiles showed high similarity values. Inter-day muscle synergy vectors had moderate similarity, while the variables regarding temporal activation were still strongly related. The present findings revealed that the muscle synergies extracted during the power clean remained stable across sets and days in unexperienced participants. Thus, the mathematical procedure for the extraction of muscle synergies through nonnegative matrix factorization (NMF) may be considered a reliable method to study muscle coordination adaptations from muscle strength programs.
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Iskandar, Risfan, Oce Wiriawan, and Sapto Wibowo. "Increasing Arm Muscle Strength and Power with Dumbbell Exercise Variations." Jurnal Maenpo : Jurnal Pendidikan Jasmani Kesehatan dan Rekreasi 13, no. 1 (June 22, 2023): 90. http://dx.doi.org/10.35194/jm.v13i1.3253.
Testo completoAbstract (sommario):
The problem of this research is the lack of exercise to increase the strength and power of the arm muscles. The aim of this research is to find out whether there is an effect of dumbbell training on the strength and power of the arm muscles. The subjects of this research were 40 members of the UNDIKMA Badminton UKM. The method used in this research is quasi-experimental with a quantitative approach. Nonequivalent Control Group Design data collection. This research uses the measurement of arm muscle strength with an expanding dynamometer and arm muscle power using a two hand medicine ball put. The results of this research are that the form of exercise from groups 1, 2, and 3 has an effect on the strength and power of the arm muscles, for a greater effect, namely in group 2 with Dumbbell Bicep Curl exercises for arm muscle strength and power. Increase in strength of 11% and power of 35%. As input for this research include: 1) For UKM members this research will gain experience in weight training and know how to do the exercise, 2) For trainers it can provide insight into badminton UKM trainers regarding forms of exercise that can increase arm strength and power.Key words: Effect of Exercise, Arm Muscle Strength, Arm Muscle Power
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Koloway, Christie Brenda Gabriella, Joshua Runtuwene, and Fima Lanra Fredrik Gerald Langi. "Kekuatan Otot Perut, Daya Ledak Otot Lengan, Tinggi Lompatan dan Hasil Pukulan Smash Penuh pada Atlet Bulutangkis." Sam Ratulangi Journal of Public Health 2, no. 1 (March 29, 2021): 022. http://dx.doi.org/10.35801/srjoph.v2i1.33887.
Testo completoAbstract (sommario):
Background: Badminton is one of the most popular sports in the world, including in Indonesia. Badminton has been around since the 1930s. The strength of the abdominal muscles contributes to a full smash during hitting. Explosive power is an important biometric ability in sports activities, because the explosive power will determine how hard people can hit, kick, jump, run and so on. Jump height is a component of physical fitness to measure leg muscle power. The purpose of this study was to analyze the correlation between abdominal muscle strength, arm muscle explosive power, jump height and the result of a full smash in badminton athletes. Methods: This is a correlational research with cross-sectional approach. This research in the Badminton Field of SMK N 2 Manado in November 2020, using an analytical method with a cross-sectional design. The population is all PB athletes in Manado. The research instrument used was for abdominal muscle strength (sit-ups), for the explosive power of the arm muscles (two hand medicine ball put test), for the height of the jump (vertical jump test), the results of the smash. Data analysis used two stages, namely univariate and bivariate. Results: The results showed that the most distributed respondents based on male sex (62%), the average value of abdominal muscle strength (25.72), the average value of arm muscle explosive power (1.52), the average value – the average jump height (2), and the average value of the smash results (16.44). The results of bivariate analysis showed that there was no relationship between abdominal muscle strength (rcount = 0.211 < rtable= 0.273), arm muscle explosive power (rcount = 0.020) < rtable = 0.273), and jump height (rcount = -0.008 < rtable = 0.273) with a smash hit. Conclusion: That can be conclude there is no correlation between abdominal muscle strength, arm muscle explosive power, and jump height with the results of smash hits.
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Achwan, Achwan, Siti Najiahtul Hasanah, and Ari Sudarsono. "Single Leg Speed Hop Pengaruh Single Leg Speed Hop Terhadap Daya Ledak Otot Tungkai Pada Pesilat." Jurnal Fisioterapi dan Kesehatan Indonesia 2, no. 2 (December 15, 2022): 108–16. http://dx.doi.org/10.59946/jfki.2022.131.
Testo completoAbstract (sommario):
ABSTRACT
 Background: The explosive power of leg muscle is the ability to exert maximum power in the shortest possible time. Muscle explosive power is important for a fighter in locking, swinging, dropping, punching, kicking and avoiding attacks from unexpected angles and directions. Ways to increase muscle explosive power include plyometric training and one of them is single leg speed hops. Research Objectives: To determine the effect of single leg speed hop pliometric exercises on increasing the explosive power of limb muscles in pesilat members at SMPN 1 Parung. Research Methods: The design of this study was quasi-experimental with "two-group pretest-posttest" with a sample of 28 people selected by purposive sampling divided into two groups, namely the treatment and control groups. Measurement of leg muscle explosive power using the Standing Long Jump Test. Results: The results of the independent t-test obtained a p-value of 0.011 (p<0.005), so Ho is rejected, which means that there is a significant effect on single leg speed hop plyometric exercises. Conclusion: There is an effect of single leg speed hop plyometric exercise on increasing the explosive power of the leg muscles of the members of SMPN 1 Parung.
 Keywords: The Explosive power leg muscle; Plyometric Exercises; Single Leg Speed Hop; Martial arts
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Josephson, Robert K., Jean G. Malamud, and Darrell R. Stokes. "The efficiency of an asynchronous flight muscle from a beetle." Journal of Experimental Biology 204, no. 23 (December 1, 2001): 4125–39. http://dx.doi.org/10.1242/jeb.204.23.4125.
Testo completoAbstract (sommario):
SUMMARYMechanical power output and metabolic power input were measured from an asynchronous flight muscle, the basalar muscle of the beetle Cotinus mutabilis. Mechanical power output was determined using the work loop technique and metabolic power input by monitoring CO2 production or both CO2 production and O2 consumption. At 35°C, and with conditions that maximized power output (60 Hz sinusoidal strain, optimal muscle length and strain amplitude, 60 Hz stimulation frequency), the peak mechanical power output during a 10 s burst was approximately 140 W kg–1, the respiratory coefficient 0.83 and the muscle efficiency 14–16 %. The stimulus intensity used was the minimal required to achieve a maximal isometric tetanus. Increasing or decreasing the stimulus intensity from this level changed mechanical power output but not efficiency, indicating that the efficiency measurements were not contaminated by excitation of muscles adjacent to that from which the mechanical recordings were made. The CO2 produced during an isometric tetanus was approximately half that during a bout of similar stimulation but with imposed sinusoidal strain and work output, suggesting that up to 50 % of the energy input may go to muscle activation costs. Reducing the stimulus frequency to 30 Hz from its usual value of 60 Hz reduced mechanical power output but had no significant effect on efficiency. Increasing the frequency of the sinusoidal strain from 60 to 90 Hz reduced power output but not CO2 consumption; hence, there was a decline in efficiency. The respiratory coefficient was the same for 10 s and 30 s bursts of activity, suggesting that there was no major change in the fuel used over this time range.The mass-specific mechanical power output and the efficiency of the beetle muscle were each 2–3 times greater than values measured in previous studies, using similar techniques, from locust flight muscles, which are synchronous muscles. These results support the hypothesis that asynchronous flight muscles have evolved in several major insect taxa because they can provide greater power output and are more efficient than are synchronous muscles for operation at the high frequencies of insect flight.
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James, R. S., V. M. Cox, I. S. Young, J. D. Altringham, and D. F. Goldspink. "Mechanical properties of rabbit latissimus dorsi muscle after stretch and/or electrical stimulation." Journal of Applied Physiology 83, no. 2 (August 1, 1997): 398–406. http://dx.doi.org/10.1152/jappl.1997.83.2.398.
Testo completoAbstract (sommario):
James, R. S., V. M. Cox, I. S. Young, J. D. Altringham, and D. F. Goldspink Mechanical properties of rabbit latissimus dorsi muscle after stretch and/or electrical stimulation. J. Appl. Physiol. 83(2): 398–406, 1997.—The work loop technique was used to measure the mechanical performance in situ of the latissimus dorsi (LD) muscles of rabbits maintained under fentanyl anesthesia. After 3 wk of incrementally applied stretch the LD muscles were 36% heavier, but absolute power output (195 mW/muscle) was not significantly changed relative to that of external control muscle (206 mW). In contrast, continuous 10-Hz electrical stimulation reduced power output per kilogram of muscle >75% after 3 or 6 wk and muscle mass by 32% after 6 wk. When combined, stretch and 10-Hz electrical stimulation preserved or increased the mass of the treated muscles but failed to prevent an 80% loss in maximum muscle power. However, this combined treatment increased fatigue resistance to a greater degree than electrical stimulation alone. These stretched/stimulated muscles, therefore, are more suitable for cardiomyoplasty. Nonetheless, further work will be necessary to find an ideal training program for this surgical procedure.
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Ferris, Scott, and Simon Maciburko. "Intercostal Nerve Transfers to Native Triceps or Free Muscle Flaps for Elbow Extension in Brachial Plexus Injuries." Journal of Brachial Plexus and Peripheral Nerve Injury 19, no. 01 (January 2024): e1-e5. http://dx.doi.org/10.1055/s-0043-1778063.
Testo completoAbstract (sommario):
AbstractIntercostal nerve donors for traumatic brachial plexus injury reconstruction have been used to neurotize native muscles or free-functioning muscle transfers, with inconsistent outcomes reported. The aim was to record a substantial series, evaluate functional outcomes, and identify prognostic factors. We present a single-surgeon case series of 21 consecutive patients who underwent 21 transfer procedures to either native muscles or free-functioning muscles to reconstruct elbow extension over a 9-year period. Outcome parameters included target muscle power grade and timing of recovery. A Medical Research Council power grade ≥ M4 was achieved in 17 reconstructions. The free-functioning muscle group had significantly higher success rate and reached their best power grade 14 months earlier. Free-functioning muscle reconstruction with intercostal nerve transfer is a more complex procedure but has quicker functional recovery and greater reliability in achieving grade M4.
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Gabaldón, Annette M., Frank E. Nelson, and Thomas J. Roberts. "Relative shortening velocity in locomotor muscles: turkey ankle extensors operate at low V/Vmax." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 294, no. 1 (January 2008): R200—R210. http://dx.doi.org/10.1152/ajpregu.00473.2007.
Testo completoAbstract (sommario):
The force-velocity properties of skeletal muscle have an important influence on locomotor performance. All skeletal muscles produce less force the faster they shorten and typically develop maximal power at velocities of ∼30% of maximum shortening velocity (Vmax). We used direct measurements of muscle mechanical function in two ankle extensor muscles of wild turkeys to test the hypothesis that during level running muscles operate at velocities that favor force rather than power. Sonomicrometer measurements of muscle length, tendon strain-gauge measurements of muscle force, and bipolar electromyographs were taken as animals ran over a range of speeds and inclines. These measurements were integrated with previously measured values of muscle Vmax for these muscles to calculate relative shortening velocity (V/Vmax). At all speeds for level running the V/Vmax values of the lateral gastrocnemius and the peroneus longus were low (<0.05), corresponding to the region of the force-velocity relationship where the muscles were capable of producing 90% of peak isometric force but only 35% of peak isotonic power. V/Vmax increased in response to the demand for mechanical power with increases in running incline and decreased to negative values to absorb energy during downhill running. Measurements of integrated electromyograph activity indicated that the volume of muscle required to produce a given force increased from level to uphill running. This observation is consistent with the idea that V/Vmax is an important determinant of locomotor cost because it affects the volume of muscle that must be recruited to support body weight.
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Robertson, D. G. E., Jean-Marie J. Wilson, and Taunya A. St Pierre. "Lower Extremity Muscle Functions during Full Squats." Journal of Applied Biomechanics 24, no. 4 (November 2008): 333–39. http://dx.doi.org/10.1123/jab.24.4.333.
Testo completoAbstract (sommario):
The purpose of this research was to determine the functions of the gluteus maximus, biceps femoris, semitendinosus, rectus femoris, vastus lateralis, soleus, gastrocnemius, and tibialis anterior muscles about their associated joints during full (deep-knee) squats. Muscle function was determined from joint kinematics, inverse dynamics, electromyography, and muscle length changes. The subjects were six experienced, male weight lifters. Analyses revealed that the prime movers during ascent were the monoarticular gluteus maximus and vasti muscles (as exemplified by vastus lateralis) and to a lesser extent the soleus muscles. The biarticular muscles functioned mainly as stabilizers of the ankle, knee, and hip joints by working eccentrically to control descent or transferring energy among the segments during ascent. During the ascent phase, the hip extensor moments of force produced the largest powers followed by the ankle plantar flexors and then the knee extensors. The hip and knee extensors provided the initial bursts of power during ascent with the ankle extensors and especially a second burst from the hip extensors adding power during the latter half of the ascent.
38
Koizumi, Kohei, Kumiko Sasao, Yoshihiro Senju, and Toyohiro Hamaguchi. "Power-Assisted Scissors Reduce Adductor Pollicis Muscle Fatigue: A Comparative Study in Female College Students." Applied Sciences 14, no. 23 (December 6, 2024): 11375. https://doi.org/10.3390/app142311375.
Testo completoAbstract (sommario):
Hand fatigue commonly occurs in repetitive tasks, such as cutting with scissors, leading to discomfort, reduced productivity, and musculoskeletal disorders. Recent advances in assistive technology have introduced power-assisted scissors to reduce the muscular load. Pinching and grasping mainly involve the adductor pollicis muscles of the hand. Measuring the electromyographic (EMG) activity of these muscles provides valuable insights into the muscular effort required for such tasks. Studies have indicated that power-assisted devices can effectively reduce muscle strain and fatigue. However, research on the effect of power-assisted scissors on adductor pollicis muscle activity is limited. This study examines the differences in adductor pollicis muscle activity using power-assisted scissors versus traditional scissors. The experiment consisted of 20 participants performing a scissor manipulation task with and without power assistance. Frequency analysis of the adductor pollicis muscle EMG data indicated that scissors with power assistance significantly reduced muscle fatigue (95% confidence interval, 10.705 [4.523–19.751], p < 0.01, η2 = 0.01). Understanding the efficacy of power-assisted scissors has significant implications for occupational health—particularly in professions that involve extensive manual cutting, such as tailoring and hairdressing. This study can contribute to the design of ergonomic tools that enhance comfort and reduce musculoskeletal disorder risks.
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Josephson, R. K., J. G. Malamud, and D. R. Stokes. "Power output by an asynchronous flight muscle from a beetle." Journal of Experimental Biology 203, no. 17 (September 1, 2000): 2667–89. http://dx.doi.org/10.1242/jeb.203.17.2667.
Testo completoAbstract (sommario):
The basalar muscle of the beetle Cotinus mutabilis is a large, fibrillar flight muscle composed of approximately 90 fibers. The paired basalars together make up approximately one-third of the mass of the power muscles of flight. Changes in twitch force with changing stimulus intensity indicated that a basalar muscle is innervated by at least five excitatory axons and at least one inhibitory axon. The muscle is an asynchronous muscle; during normal oscillatory operation there is not a 1:1 relationship between muscle action potentials and contractions. During tethered flight, the wing-stroke frequency was approximately 80 Hz, and the action potential frequency in individual motor units was approximately 20 Hz. As in other asynchronous muscles that have been examined, the basalar is characterized by high passive tension, low tetanic force and long twitch duration. Mechanical power output from the basalar muscle during imposed, sinusoidal strain was measured by the work-loop technique. Work output varied with strain amplitude, strain frequency, the muscle length upon which the strain was superimposed, muscle temperature and stimulation frequency. When other variables were at optimal values, the optimal strain for work per cycle was approximately 5%, the optimal frequency for work per cycle approximately 50 Hz and the optimal frequency for mechanical power output 60–80 Hz. Optimal strain decreased with increasing cycle frequency and increased with muscle temperature. The curve relating work output and strain was narrow. At frequencies approximating those of flight, the width of the work versus strain curve, measured at half-maximal work, was 5% of the resting muscle length. The optimal muscle length for work output was shorter than that at which twitch and tetanic tension were maximal. Optimal muscle length decreased with increasing strain. The curve relating work output and muscle length, like that for work versus strain, was narrow, with a half-width of approximately 3 % at the normal flight frequency. Increasing the frequency with which the muscle was stimulated increased power output up to a plateau, reached at approximately 100 Hz stimulation frequency (at 35 degrees C). The low lift generated by animals during tethered flight is consistent with the low frequency of muscle action potentials in motor units of the wing muscles. The optimal oscillatory frequency for work per cycle increased with muscle temperature over the temperature range tested (25–40 degrees C). When cycle frequency was held constant, the work per cycle rose to an optimum with increasing temperature and then declined. We propose that there is a temperature optimum for work output because increasing temperature increases the shortening velocity of the muscle, which increases the rate of positive work output during shortening, but also decreases the durations of the stretch activation and shortening deactivation that underlie positive work output, the effect of temperature on shortening velocity being dominant at lower temperatures and the effect of temperature on the time course of activation and deactivation being dominant at higher temperatures. The average wing-stroke frequency during free flight was 94 Hz, and the thoracic temperature was 35 degrees C. The mechanical power output at the measured values of wing-stroke frequency and thoracic temperature during flight, and at optimal muscle length and strain, averaged 127 W kg(−1)muscle, with a maximum value of 200 W kg(−1). The power output from this asynchronous flight muscle was approximately twice that measured with similar techniques from synchronous flight muscle of insects, supporting the hypothesis that asynchronous operation has been favored by evolution in flight systems of different insect groups because it allows greater power output at the high contraction frequencies of flight.
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Aerts, P. "Vertical jumping in Galago senegalensis: the quest for an obligate mechanical power amplifier." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 353, no. 1375 (October 29, 1998): 1607–20. http://dx.doi.org/10.1098/rstb.1998.0313.
Testo completoAbstract (sommario):
Bushbabies ( Galago senegalensis ) are renowned for their phenomenal jumping capacity. It was postulated that mechanical power amplification must be involved. Dynamic analysis of the vertical jumps performed by two bushbabies confirms the need for a power amplifier. Inverse dynamics coupled to a geometric musculo–skeletal model were used to elucidate the precise nature of the mechanism powering maximal vertical jumps. Most of the power required for jumping is delivered by the vastus muscle–tendon systems (knee extensor). Comparison with the external joint–powers revealed, however, an important power transport from this extensor (about 65%) to the ankle and the midfoot via the bi–articular calf muscles. Peak power output likely implies elastic recoil of the complex aponeurotic system of the vastus muscle. Patterns of changes in length and tension of the muscle–tendon complex during different phases of the jump were found which provide strong evidence for substantial power amplification (times 15). It is argued here that the multiple internal connective tissue sheets and attachment structures of the well–developed bundles of the vastus muscle become increasingly stretched during preparatory crouching and throughout the extension phase, except for the last 13 ms of the push–off (i.e. when power requirements peak). Then, tension in the knee extensors abruptly falls from its maximum, allowing the necessary fast recoil of the tensed tendon structures to occur.
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Nopin, Sergei, Yulia Koryagina, Gukas Ter-Akopov, and Sabina Abutalimova. "Dynamics of muscle electric activity parameters and maximum power characteristics in different phases of performance of weightlifting snatch." Russian Journal of Biomechanics 25, no. 4 (December 30, 2021): 329–37. http://dx.doi.org/10.15593/rjbiomech/2021.4.04.
Testo completoAbstract (sommario):
Weightlifting exercises are coordinately complex, speed and power based movements, which simultaneously combine the maximum muscle work with different contraction types and limit the result with special functional features of the neuromuscular apparatus. According to modern views, indicators of biomechanics of the motor act and electromyographic characteristics of leading muscles during performance of the act show different aspects of the same process of contraction and can be used as criteria for an evaluation of muscle efforts and the functional state of the neuromuscular apparatus. The objective of this study is to identify special features of dynamics of muscle electric activity parameters and maximum power characteristics in different phases of weightlifting snatch. The study involved 35 male elite weightlifters with the Master of Sports qualification. The study was conducted with the BTS Motion System (made by BTS Bioengineering, Italy). A computer program was developed to analyze the technique of the snatch (the certificate RU 2020660142 from 28.08.2020). The study included registration and following analysis of biomechanical (dynamic, kinematic) and electromyographic indicators during performance of the snatch by athletes with 80 % intensity of the maximum weight directly during the training session. Features of dynamics of muscles’ electric activity parameters and maximum power characteristics, which are significantly changing in different phases of performance of the snatch, were revealed in the study. Pull phases are characterized by the increase of muscle tension, muscle work in the concentric dynamic contraction. Snatch phases are characterized by the maximum power of muscle tension and the speed of its dynamics according to both biomechanical features and electrical processes in muscles: a maximum tension and high frequency of impulsion of motor units of extensor muscles were noted. Squat phases are characterized by the decrease of muscle tension and speed of its changing, muscle work in the combined type of contraction, including eccentric and static types. High, but not maximum indicators of power and tension of muscles characterize phases of standing-up. It was revealed that the eccentric muscle contraption, according to EMG indicators, is manifested in the decrease of both amplitude and frequency characteristics. The concluded study allowed to present data characterizing biomechanics of the motor act and special physiological features of leading muscles’ work of elite weightlifters during performance of the exercise. Power and electromyographic parameters in various types of muscle work in different phases of the snatch were determined.
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Romadi, Tomoliyus, Alim Abdul, Budiarti Ratna, and Kustriyono Munajad Sigit. "Relationship between Arm Length, Power Arm Muscles and Power Lemb Muscles on Butterfly Style Swimming Achievement." INTERNATIONAL JOURNAL OF MULTIDISCIPLINARY RESEARCH AND ANALYSIS 07, no. 06 (May 12, 2024): 2636–42. https://doi.org/10.5281/zenodo.12526362.
Testo completoAbstract (sommario):
This study aims to determine the relationship between arm length, arm muscle power and leg muscle power on butterfly swimming performance. This research uses a survey method. Data collection techniques use tests and measurements. The population in this study were swimming athletes aged 12 to 13 years in the Special Region of Yogyakarta Province. The research used was population research with a total of 27 athletes. The main instruments used are the arm length test, arm muscle power test, leg muscle power test and 25 meter butterfly swimming test. The data analysis used is the normality test, linearity test, correlation test and multiple regression analysis test with a significance level of 5%. The results showed that the relationship between arm length and butterfly swimming performance was 0.617, the relationship between arm muscle power and butterfly swimming performance was 0.460, the relationship between leg muscle power and butterfly swimming performance was 0.838 and the relationship between arm length, arm muscle power and leg muscle power on butterfly swimming performance is 0.897. The correlation between arm length is greater than arm muscle power because each athlete's butterfly swimming technique is not the same (how much the elbow bends when the arm is pulled).
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Syme, Douglas A., and Robert E. Shadwick. "Effects of longitudinal body position and swimming speed on mechanical power of deep red muscle from skipjack tuna (Katsuwonus pelamis)." Journal of Experimental Biology 205, no. 2 (January 15, 2002): 189–200. http://dx.doi.org/10.1242/jeb.205.2.189.
Testo completoAbstract (sommario):
SUMMARY The mechanical power output of deep, red muscle from skipjack tuna (Katsuwonus pelamis) was studied to investigate (i) whether this muscle generates maximum power during cruise swimming, (ii) how the differences in strain experienced by red muscle at different axial body locations affect its performance and (iii) how swimming speed affects muscle work and power output. Red muscle was isolated from approximately mid-way through the deep wedge that lies next to the backbone; anterior (0.44 fork lengths, ANT) and posterior (0.70 fork lengths, POST) samples were studied. Work and power were measured at 25°C using the work loop technique. Stimulus phases and durations and muscle strains (±5.5 % in ANT and ±8 % in POST locations) experienced during cruise swimming at different speeds were obtained from previous studies and used during work loop recordings. In addition, stimulus conditions that maximized work were determined. The stimulus durations and phases yielding maximum work decreased with increasing cycle frequency (analogous to tail-beat frequency), were the same at both axial locations and were almost identical to those used by the fish during swimming, indicating that the muscle produces near-maximal work under most conditions in swimming fish. While muscle in the posterior region undergoes larger strain and thus produces more mass-specific power than muscle in the anterior region, when the longitudinal distribution of red muscle mass is considered, the anterior muscles appear to contribute approximately 40 % more total power. Mechanical work per length cycle was maximal at a cycle frequency of 2–3 Hz, dropping to near zero at 15 Hz and by 20–50 % at 1 Hz. Mechanical power was maximal at a cycle frequency of 5 Hz, dropping to near zero at 15 Hz. These fish typically cruise with tail-beat frequencies of 2.8–5.2 Hz, frequencies at which power from cyclic contractions of deep red muscles was 75–100 % maximal. At any given frequency over this range, power using stimulation conditions recorded from swimming fish averaged 93.4±1.65 % at ANT locations and 88.6±2.08 % at POST locations (means ± s.e.m., N=3–6) of the maximum using optimized conditions. When cycle frequency was held constant (4 Hz) and strain amplitude was increased, work and power increased similarly in muscles from both sample sites; work and power increased 2.5-fold when strain was elevated from ±2 to ±5.5 %, but increased by only approximately 12 % when strain was raised further from ±5.5 to ±8 %. Taken together, these data suggest that red muscle fibres along the entire body are used in a similar fashion to produce near-maximal mechanical power for propulsion during normal cruise swimming. Modelling suggests that the tail-beat frequency at which power is maximal (5 Hz) is very close to that used at the predicted maximum aerobic swimming speed (5.8 Hz) in these fish.
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Bobbert, Maarten F., L. J. Richard Casius, Stephan van der Zwaard, and Richard T. Jaspers. "Effect of vasti morphology on peak sprint cycling power of a human musculoskeletal simulation model." Journal of Applied Physiology 128, no. 2 (February 1, 2020): 445–55. http://dx.doi.org/10.1152/japplphysiol.00674.2018.
Testo completoAbstract (sommario):
Fascicle length of m. vastus lateralis in cyclists has been shown to correlate positively with peak sprint cycling power normalized for lean body mass. We investigated whether vasti morphology affects sprint cycling power via force-length and force-velocity relationships. We simulated isokinetic sprint cycling at pedaling rates ranging from 40 to 150 rpm with a forward dynamic model of the human musculoskeletal system actuated by eight leg muscles. Input of the model was muscle stimulation over time, which was optimized to maximize the average power output over a pedal cycle. This was done for a reference model and for models in which the vasti had equal volume but different morphology. It was found that models with longer muscle fibers but a reduced physiological cross-sectional area of the vasti produced a higher sprint cycling power. This was partly explained by better alignment of the peak power-pedaling rate curve of the vasti with the corresponding curves of the other leg muscles. The highest sprint cycling power was achieved in a model in which the increase in muscle fiber length of the vasti was accompanied by a concomitant shift in optimum knee angle. It was concluded that muscle mechanics can partly explain the positive correlations between fascicle length of m. vastus lateralis and normalized peak sprint cycling power. It should be investigated whether muscle fiber length of the vasti and optimum knee angle are suitable training targets for athletes who want to concurrently improve their sprint and endurance cycling performance. NEW & NOTEWORTHY We simulated isokinetic sprint cycling at pedaling rates ranging from 40 to 150 rpm with a forward dynamic model of the human musculoskeletal system actuated by eight leg muscles. We selectively modified vasti morphology: we lengthened the muscle fibers and reduced the physiological cross-sectional area. The modified model was able to produce a higher sprint cycling power.
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Radermecker, M. A., F. Chaussende, C. Struble, P. A. Grandjean, J. Fourny, B. Focant, P. Gerard, D. Serteyn, and R. Limet. "Biomechanical Characteristics of Unconditioned and Conditioned Latissimus Dorsi Muscles Used for Cardiocirculatory Assistance." Cardiovascular Surgery 5, no. 5 (October 1997): 516–25. http://dx.doi.org/10.1177/096721099700500516.
Testo completoAbstract (sommario):
An understanding of the biomechanical characteristics of striated skeletal muscles involved in cardiocirculatory assistance is a prerequisite to assess their efficacy and to evaluate their haemodynamic benefits. Six goats had their latissimus dorsi muscles evaluated by isometric strain gauge testing. Total tension, and both active and passive force development at different preloads were measured. The relationship between muscle impedance and starting length was also studied. Four additional muscles were submitted to isometric and isotonic strain gauge testing after 3 months of chronic electrical stimulation (Broussais Hospital protocol) with the contralateral muscle serving as a control. In isometric testing, both conditioned and unconditioned goat latissimus dorsi displayed a Frank-Starling length-tension curve, and a linear relationship between muscle impedance and starting length was found. Chronic stimulation preserved muscle mass and isometric force. Transformed muscles showed a mean 59% reduction of maximal shortening velocity; means (s.d.) residual shortening velocity at maximal work and power output was 0.17(0.07) m/s. The work and power ouput were both reduced 65% after stimulation, and the residual maximal power at optimal preload varied from approximately 7.7 and 9.6 W/kg. It is concluded that, following the Broussais protocol, the goat latissimus dorsi muscle retained mass and most of its isometric force-generating capacity, but lost significant work and power potential. The residual power output did not, however, preclude the possibility of a significant cardiocirculatory contribution, providing that the conditions for optimal energy transduction are adequately delineated.
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Rival, Arivaldy, Doni Doni, Argantos Argantos, Yogi Setiawan, and Yendrizal Yendrizal. "The Contribution of Arm Muscle Strength and Limb Muscle Explosive Power to the 50 Meter Butterfly Swim." Jurnal Gladiator 3, no. 1 (February 13, 2023): 1–15. https://doi.org/10.24036/gltdor91011.
Testo completoAbstract (sommario):
The purpose of writing this article is to determine the contribution of arm muscle strength and leg muscle explosive power to the 50 meter butterfly stroke swimming ability of Specialized Swimming Students, FIK UNP Training Department. This type of research is correlational research. This research was conducted in May 2021 at the FIK UNP Padang swimming pool. In writing this article a sample of 20 students. The instrument in this study used 1) medical ball throwing, 2) standing broad jump test and 3) the 50 meter butterfly swimming test. The analysis technique used simple correlation analysis and multiple correlations. Data analysis showed that: 1) Arm muscle strength contributed 78.09% to the 50 Meter Butterfly Swimming Ability. 2) The explosive power of the leg muscles contributes to the 50 Meter Butterfly Swim Ability by 25.50%, 3) The arm muscle strength and the leg muscle explosive power contribute together to the 50 Meter Butterfly Swim Ability by 78.50 %. Keywords: Arm Muscle Strength, Limb Muscle Explosive Power, 50 meter swimming butterfly power
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Trappe, S., P. Gallagher, M. Harber, J. Carrithers, W. Evans, and T. Trappe. "MUSCLE POWER WITH AGING." Medicine & Science in Sports & Exercise 34, no. 5 (May 2002): S98. http://dx.doi.org/10.1097/00005768-200205001-00544.
Testo completo
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Alexander, R. McNeill. "Flexing our muscle power." Nature 416, no. 6883 (April 2002): 793. http://dx.doi.org/10.1038/416793a.
Testo completo
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Eglseer, Doris, Ruth Poglitsch, and Regina Elisabeth Roller-Wirnsberger. "Muscle power and nutrition." Zeitschrift für Gerontologie und Geriatrie 49, no. 2 (December 18, 2015): 115–19. http://dx.doi.org/10.1007/s00391-015-1008-7.
Testo completo
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Roberts, Thomas J. "Some Challenges of Playing with Power: Does Complex Energy Flow Constrain Neuromuscular Performance?" Integrative and Comparative Biology 59, no. 6 (June 26, 2019): 1619–28. http://dx.doi.org/10.1093/icb/icz108.
Testo completoAbstract (sommario):
Abstract Many studies of the flow of energy between the body, muscles, and elastic elements highlight advantages of the storage and recovery of elastic energy. The spring-like action of structures associated with muscles allows for movements that are less costly, more powerful and safer than would be possible with contractile elements alone. But these actions also present challenges that might not be present if the pattern of energy flow were simpler, for example, if power were always applied directly from muscle to motions of the body. Muscle is under the direct control of the nervous system, and precise modulation of activity can allow for finely controlled displacement and force. Elastic structures deform under load in a predictable way, but are not under direct control, thus both displacement and the flow of energy act at the mercy of the mechanical interaction of muscle and forces associated with movement. Studies on isolated muscle-tendon units highlight the challenges of controlling such systems. A carefully tuned activation pattern is necessary for effective cycling of energy between tendon and the environment; most activation patterns lead to futile cycling of energy between tendon and muscle. In power-amplified systems, “elastic backfire” sometimes occurs, where energy loaded into tendon acts to lengthen active muscles, rather than accelerate the body. Classic models of proprioception that rely on muscle spindle organs for sensing muscle and joint displacement illustrate how elastic structures might influence sensory feedback by decoupling joint movement from muscle fiber displacements. The significance of the complex flow of energy between muscles, elastic elements and the body for neuromotor control is worth exploring.